sindresorhus/ow
Ow
ow is a type-safe schema validation library for TypeScript that verifies data integrity at runtime. It functions as a runtime validation framework and type guard utility, ensuring that JavaScript values match expected types and schemas before they are processed.
The library synchronizes runtime data checks with static TypeScript type definitions, allowing users to extract type definitions directly from validation predicates. This integration enables type narrowing, where a successful validation result refines the variable type for safer usage in the code.
The framework uses a chainable API to build verification logic for function arguments and object shapes. It supports the composition of complex predicates using logical operators, the definition of reusable validators, and the customization of error messages. Support is included for validating primitives, built-in objects, and typed arrays.
Features
- Runtime Schema Validations - Verifies that JavaScript values match expected TypeScript types and schemas during runtime execution.
- Predicate Composers - Combines multiple validation rules using logical operators to create sophisticated constraints for data.
- Runtime Validation Libraries - Provides runtime data verification combined with automatic TypeScript type inference.
- Type Narrowing - Tests values against predicates to refine the TypeScript type upon a successful match.
- Type Narrowing Assertion - Refines TypeScript types by linking runtime validation success to static type guards for safer variable usage.
- Type Validation - Provides runtime checking to ensure values match specific types, including primitives and built-in objects.
- Data Schema Enforcement - Enforces complex rules and requirements for objects and primitives to catch malformed information early in the application flow.
- Object Shape Validation - Enforces specific property requirements and types on objects while supporting partial updates.
- Type-Safe Schema Validators - Synchronizes runtime data checks with static TypeScript type definitions to ensure type safety during validation.
- Function Argument Validation - Verifies that inputs passed to functions meet specific type constraints and requirements at runtime.
- Logical Predicate Composition - Combines individual validation functions using logical operators to create sophisticated requirements for complex data structures.
- Chainable Validation APIs - Uses a chainable API to build complex validation logic through incrementally refined method calls.
- Single Value Validators - Verifies that a single value matches a specific predicate and triggers an error upon failure.
- Schema Type Inference - Automatically extracts TypeScript type definitions from runtime predicates to ensure consistency without duplicating code.
- Runtime Type Guards - Provides runtime boolean checks that automatically narrow TypeScript types upon a successful match.
- Build-Time Code Stripping - Implements environment-aware markers to strip validation logic from production bundles to reduce final application size.
- Predicate Combinations - Allows combining several constraints to require a minimum number of matches or invert the result of a rule.
- Predicate Match Verification - Returns a boolean indicating whether a value satisfies a predicate without triggering an exception.
- Fluent Validation APIs - Uses a chainable, fluent API to build complex verification logic for function arguments and object shapes.
- Custom Validation Functions - Executes custom synchronous or asynchronous validation logic with support for specific error messages.
- Function Registries - Provides a registry mechanism to map identifiers to reusable standalone validation functions.
- Composable Validation Frameworks - Implements a framework for creating reusable, composable predicates and custom error messages for complex data verification.
- Explicit Nullable Validators - Allows specifying whether values can be undefined or null without triggering validation errors.
- Validation Error Customizations - Provides mechanisms for overriding default error messages with specific text or dynamic functions.
- Reusable Validators - Enables the definition of reusable validation rules with custom labels to maintain consistency across projects.
- Runtime Validation - Human-readable function argument validation.
